Republican debate as it happened: Four GOP candidates go head-to-head in Detroit

That's a wrap for our live coverage of tonight's GOP debate. Thanks for joining us!

Closing statements:

• Kasich discusses his experience in Ohio and says he will fix Washington.
• Rubio says this has been an unusual campaign season, but says it's all about opportunities.
• Cruz directs his message to the military and to law enforcement: I have your back.
• Trump says he will bring jobs back, will fix the military & strengthen the border.

We're nearing the end of tonight's debate. Last question: Can you definitively support the Republican nominee if it's Donald Trump?

• Marco Rubio: Yes, because the GOP needs to rally against the Democrats.
• Ted Cruz: Yes
• John Kasich: Yes, but he believes he will be the party's nominee.

Trump is asked if he would support the Republican nominee if it's not him. "If it's not me?" he asks, before he confirms he would support the GOP nominee.

Wouldn't it be nice if we could get along with Russia?

- Trump after Rubio brings up Russian President Vladimir Putin's praise of Trump

And then this interaction happened:

Issues are being quickly discussed. Cruz and Trump are asked about gay adoption. They both claim they support states making those decisions.

Rubio, meanwhile, is asked about the Second Amendment. He says he will support the Second Amendment if elected. Trump is also asked about his previous support of an assault weapons ban, which he says he no longer supports. He brings up the Paris terrorists attacks and claims if Parisians were armed, there would have been fewer victims.

With just 30 minutes left in the debate, discussion turns into social issues. Kasich is asked about his comments regarding religious liberties and gay marriage. Kasich appears to initially support his previous remarks but says that no one should be forced to participate in something they do not support due to religious reasons. "If you go to a photographer to take pictures at your wedding and he says he'd rather not do it, find another photographer," he says.

We as adults have to fight in our neighborhoods, in our communities for our children's education. Put the politics aside.

-Kasich on schools in Cleveland, Ohio

After a brief commercial break, we're back with a question on Flint, Michigan and the water crisis in the largely Black and largely poor city. Rubio is asked about the crisis and the response by Democratic candidates Hillary Clinton and Bernie Sanders. "What happened in Flint was a terrible thing," Rubio said, but added he did not believe any Republican leader woke up one day and decided to poison the water source.

He's trying to do to the American people what he did to the people of that course.

- Rubio on Trump

Rubio brings up Trump University and the major controversy surrounding it. Trump claims his Trump University has an A rating from the Better Business Bureau and 98% positive rating. However, Megyn Kelly is quick to bring up the real facts. Trump University actually had a D- rating from the BBB. She also pointed out that several Trump U participants asked for a refund and complained about what they received.

Megyn Kelly is taking Trump to task. She's playing three clips showing how quickly he changes his views, in particular in regards Afghanistan, Syrian refugees and whether President George W Bush lied to get the US into Iraq. Trump defends himself by saying: "I have a very strong core. But I've never seen a successful person who wasn't flexible."

Discussion turns to terrorism. Trump says he will be strong against terrorism, including bringing back torture practices like waterboarding. He also reiterated his support for killing the families of terrorists. He then refers to "these animals over in the Middle East chopping off heads".

Recent reports suggest the military might not follow a President Trump's order to violate the Geneva Convention. "I'm a leader," he says. "If I say do it, they're going to do it, that's what leadership is about."

Trump is asked about hiring immigrants for his hotel Mar-a-Lago in Florida. He claims that he hires from abroad because American citizens are not willing to work in short-term jobs that only last between November and March. Rubio argues against that claim, while Cruz renews his call for Trump to release the NYT tapes. The Florida senator brings up the NYT report that found 300 US citizens had applied for those jobs but only 17 had been hired.

When asked if he would allow the New York Times to release the off-the-record interview he had with its editorial staff, Trump said he "respected" the process too much to allow its release.

Rubio was quick to point out: "If tonight you tell the New York Times to release the audio, they will do it."

Debate turns immigration reform. Cruz is asked why Senator Session endorsed Trump. "If you look to the actual record," Cruz claims that he is most likely to support for a tough immigration policy.

In his attack, Cruz accuses Trump of supporting Carter over Reagan, and Kerry over Bush. "He funded Harry Reid and Nancy Pelosi taking over Congress to pass Obamacare," he continues. The Texas senator adds that Trump supported five of the eight members of the Gang of 8 immigration reform.

Cruz also notes Trump wrote several checks to Clinton in 2008, adding, "It wasn't for business."

Trump is asked what he would cut to to make up for the deficit. He says he would cut the Department of Education and the Environmental Protection Agency. However, he's challenged by moderator Chris Wallace, who says the numbers don't add. The DOE and EPA have a combined budget of $86m budget. The deficit is $544m per annum.

He doesn't have answers and he's asking us to make him the president of the United States of America.

-Rubio on Trump

The fight has turned into who can beat Democrat Hillary Clinton in a general election. Trump maintains that he can beat the Democratic frontrunner, which Rubio and Cruz dispute. John Kasich jumps in to note that polls show he can beat Clinton by the widest margin.

Marco Rubio is on the chopping block next. He's asked why he's gone on the attack against Trump, to which he responds that he's simply returning the favour of Trump's attacks to everyone this campaign season.

And we're off. First question, unsurprisingly, goes to Donald Trump, who is asked about Mitt Romney's criticisms earlier today. Trump slams Romney for being a "failed candidate" in the 2012 election against President Barack Obama.

The candidates are gearing up for quite the fight tonight. Marco Rubio, who earned a win in Minnesota on Tuesday, assured supporters that he would not be dropping out of the race. Early in the day, Rubio sent the follow message to his supporters:

This race is just beginning. The momentum surrounding our campaign has never been stronger: Just last week our campaign was polling 20 points below Donald Trump in Virginia and Tuesday we nearly tied him and won essentially the same number of delegates.

While the media would love to have you think that their preferred candidate--Trump--is running away with this election, that is not true. This race is NARROWING. And soon we will be winning more than Trump.

He also shared this video to get viewers to tune in to tonight's debate.

Welcome to our live coverage of the 11th Republican debate. We're just minutes away from four of the remaining GOP candidates battling it out to earn the support of voters across the US following an eventful Super Tuesday.